Workers using hand held, air or power tools is manual handling and may be exposed to harmful levels of hand arm vibration (HAV). By minimising vibration exposure, you can reduce the risk of musculoskeletal disorders (MSD).
What is hand arm vibration?
HAV is transmitted to the hands and arms by:
- Using hand held power or air tools
- Hand guided machinery like powered lawn mowers or
- Holding materials being processed by machinery
People using tools such as ack hammers, hammer drills, grinders, riveters, chain saws, and impact wrenches can experience HAV.
What are the adverse health effects of exposure to HAV?
There are many adverse effects such as disrupted circulation, damage to nerves resulting in tingling and or numbness in the hand, damage to tendons, muscles, bones and joints, specifically disorders such as carpal tunnel syndrome and vibration white finger may result from exposure to HAV. Slow or rapid closing down of blood circulation may also result from HAV due to exposure for a long periods and /or exposure over many years.
When you inspect your hands, you may notice whitening of the fingers and this can be highlighted in cold weather or cold conditions. MSDs may also result from vibration and noise exposure at the same time. Workers exposed to vibration while carrying out manual tasks may also notice pain in their hands and arms and reduced muscle strength and even grip.
Factors influencing the adverse effects of exposure to HAV
- Higher vibration emissions
- Larger surface area of hand in contact with tool
- Poor tool maintenance
- Little or no handle insulation
- Heavy tools
- Long exposure during each daily shift and/or work
- Harder material being worked with
- Bad working postures and working overhead
- Short or few rest periods
- Cold temperatures
- Gripping the handle more tightly than needed
- Low operator skill or poor technique
- Lifestyle factors such as smoking
- Medical history such as disease or prior injury to fingers, hand or wrists
Workers who report tingling or numbness of the hands or arms after using vibrating tools may indicate a problem. Controls should immediately be put in place.
Eliminating and minimising vibration exposure
Eliminating or minimising exposure to HAV usually involves isolation or cushioning methods. Trialling of new hand tools in consultation with the on-site operators is vital. Gathering manufacturers testing data is also a vital control.
Controls Hierarchy for HAV
To control the adverse effects of HAV more than one control may be necessary. This scale should be worked up and down to select appropriate controls to be used.
It is important to note that gloves should not be relied upon to protect workers from vibration. They only provide protection from cold temperatures, water, cuts and abrasions. The use of thick gloves may make HAV exposure worse if a worker applies too much grip force to the tool. An under powered or blunt tool may take longer to do a job, thus exposing the worker to increased time of exposure.
Do you need to measure vibration?
Measurement of HAV exposure may be needed if;
- There is not enough information on the vibration emission of the tool
- The vibration levels are likely to be high
- The tool is used for long periods of time
Source: Safe Work Australia
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